When a silicon controlled rectifier (SCR) is triggered, to what other semiconductor diode are its electrical characteristics similar (as measured between its cathode and anode)?

When a Silicon Controlled Rectifier (SCR) receives a trigger signal at its gate, it latches "on" and allows current to flow from the anode to the cathode. In this triggered state, its internal semiconductor layers essentially act just like a standard PN junction diode that is forward-biased. Like a standard junction diode, it only allows current to flow in one direction and exhibits a characteristic forward voltage drop. It will continue to act like this standard diode until the forward current drops below its holding current limit. The distractor diodes have highly specialized functions that do not match a triggered SCR. A varactor diode acts as a voltage-controlled capacitor, a PIN diode is typically used as an RF switch, and a Schottky diode features an unusually low forward voltage drop and very fast switching action.